Is a butcher and proprietor of Hilary Briss and Son, Royston Vasey local butchers. His wares include a secret "special stuff", a highly addictive and mysterious substance, which, it is implied, is not only illegal but hideously immoral. Many authority figures are "in" on Briss' activities, including Police Inspector Cox, Magistrate Maurice Evans (Pemberton) and Councillor Samuel Chignell (Shearsmith), all of whom become hopelessly addicted.
Though Briss only sells his "special stuff" to a select group of gentlemen (often in cosy fireside gatherings at Briss' home), in Season 2 addiction to the "special stuff" led to a hemorrhagic epidemic--that is, chronic nose bleeding. This resulted in the death of many local residents, including the Mayor. The "special stuff" had reached a wider market through Evans' wife Eunice, who served it at her sandwich stall. She had gained access to the "special stuff" presumably through Maurice. The pure dose of "special stuff" which Briss served was one thing, but Eunice cut the substance and mixed it with her own paste, making it poisonous.
Before he could be caught, Briss escaped to a tropical island (where he continued selling his "special stuff") leaving behind his wife, who it turns out is a brown cow. Eunice was arrested along with Inspector Cox, while Sam and Maurice are last seen with nosebleeds, burning evidence of the "special stuff". Maurice appears to survive as he is talked about by Eunice in Season 3, but we don't know if Sam also survived. Briss did not appear in Season 3; all we know of him is a newspaper showing a story of a nosebleed epidemic in the Caribbean, suggesting his antics continued there in much the same way as before. However, in the film The League of Gentlemen's Apocalypse (not considered canon to the series), he returns clad in handcuffs and being chased by the police across the moors. Whereas in the first two seasons, Briss is clearly a villain, in the film, he is fleshed out into the anti-hero of the piece before being killed by Dr Pea, the film's parody of occultist John Dee.
Though it is never revealed what "special stuff" consists of, many have assumed that it is human meat. However, the writers have denied that this is the case, stating that they can think of "nothing more mundane than cannibalism", and indicating that it is something much worse. However, the Season 1 DVD includes a fragment of brainstorming materials in its bonus section, on which the idea of the butcher selling human appendices obtained from the local hospital is listed. Others suspect it is a highly addictive substance like cocaine, given various clues throughout Seasons 1 and 2. As revealed in season 2, Hilary's wife is a cow. Some may believe that the special stuff might be the meat of some kind of cow human hibrid that comes from his intercourse with the cow. Even the writers were apparently not sure what the special stuff was at the beginning of the series. When Briss takes Maurice along with him to receive a "special delivery" from deep in a dark forest, we see whom he gets the special stuff from: a tall ominous figure accompanied by a hunchbacked figure. It is shown that even Briss seems absolutely terrified of them. The only clue from the original live shows as to what the substance is that it rhymes with "drawstring", which has led some fans to believe that the "special stuff" is circumcised foreskins. Another clue is that the Hebrew for circumcision is Brit milah,  which, when used in everyday English, is known as a "Brit"--or, more regularly--a "Bris."
According to the character biography in Series 1, Briss says that his age "spans great oceans of time".